Pan Size Converter

How to Use This Converter

Pick your original pan shape and size, then enter the new pan you want to use. The calculator figures out the scaling factor based on surface area. Use the presets or quick conversion buttons to save time.

Pan dimensions are always measured on the inside, from one inner edge to the other—not including the rim.

Why Area Matters More Than Diameter

Pan conversion is about surface area, not diameter. When batter spreads across a pan, the area determines thickness. A 9" round pan has about 63.6 square inches of surface area (πr²). An 8" square pan has 64 square inches. That's why they're interchangeable—nearly identical area means nearly identical batter thickness.

The math isn't intuitive. Doubling a pan's diameter quadruples its area. Going from 8" to 10" round increases area by 56%, so you'd need to scale up your recipe by more than half just to keep the same thickness.

Round vs Square vs Rectangular

Round pans heat most evenly—heat travels equal distances from edges to center. Square and rectangular pans have corners where batter gets hit with heat from two sides, producing crunchier corner pieces. A 9×13" rectangular pan holds about the same as two 9" round pans, which is why most people use it for turning layer cakes into sheet cakes.

The Scaling Factor

Divide the new pan's area by the original pan's area. That's your scaling factor. A 9" round (63.6 sq in) to a 6" round (28.3 sq in) gives you 28.3 ÷ 63.6 = 0.44. Use 44% of each ingredient.

Baking Time Changes

Thicker batter takes longer. Thinner batter cooks faster. Rough rule: cut time by 15% when you double the surface area, add 20% when you halve it. But don't trust the timer—test for doneness.

Pan Materials

• Light aluminum: Even heating, pale crust, good for delicate cakes
• Dark/nonstick: Absorbs heat fast, darker crust—reduce temp 25°F
• Glass: Poor conductor but holds heat, reduce temp 25°F
• Silicone: Insulates batter, needs longer bake time, minimal browning

Bundt and Tube Pans

These are rated by cup capacity because their shapes make area calculations pointless. A 10-cup Bundt holds about the same as a 9×13" pan. A 12-cup Bundt matches two 9" round layers.

Cupcake Yields

Standard cupcakes take about 3 tablespoons of batter each (filled two-thirds). A 9" round recipe makes about 24. Minis need 1 tablespoon and yield 48-60. Jumbos take half a cup and produce 8-10. Check them a few minutes early—small portions overbake fast.

How Much to Fill

• Cakes: ⅔ full—leaves room to rise
• Cheesecakes: Can fill higher since they barely rise
• Brownies/bars: ¾ full is fine—dense batters don't climb

Before You Swap Pans

Test the volume first. Fill the new pan with water and measure. If your calculated scaling factor is between 0.9 and 1.1, you can usually skip the math and just use the recipe as-is.

Some things shouldn't be swapped. Angel food needs the tube for structure. Cheesecake needs the springform for extraction. If you're unsure, go with a slightly bigger pan.